JP6798003B2 - Manufacturing method of metal-filled microstructure - Google Patents

Description

The present invention relates to a method for producing a metal-filled microstructure.

A metal-filled microstructure (device) in which micropores provided in an insulating base material are filled with metal is one of the fields that have been attracting attention in nanotechnology in recent years. For example, it is used as an anisotropic conductive member. Is expected.
Since the heterogeneous conductive member can obtain an electrical connection between the electronic component and the circuit board simply by inserting it between the electronic component such as a semiconductor element and the circuit board and applying pressure, the electronic component such as the semiconductor element can be used. It is widely used as an electrical connection member and an inspection connector for functional inspection.

As such an anisotropic conductive member, Patent Document 1 states, "Aluminum substrate is anodized on one surface, and micropores and micropores existing on one surface of the aluminum substrate in the thickness direction are provided. An anodic oxidation treatment step of forming an anodic oxide film having a barrier layer existing at the bottom of the anodic oxide film, a barrier layer removal step of removing the barrier layer of the anodic oxide film after the anodic oxidation treatment step, and the barrier layer. After the removal step, a metal filling step of performing electrolytic plating treatment to fill the inside of the micropore with metal, and after the metal filling step, a substrate removing step of removing the aluminum substrate to obtain a metal-filled microstructure. A method for producing a metal-filled microstructure having and. ”([Claim 1]).

International Publication No. 2015/029881

The present inventor examined the method for producing a metal-filled microstructure described in Patent Document 1, and found that in the metal filling step after the barrier layer removing step, depending on the conditions of the electroplating treatment, the metal inside the micropores. It was found that there is a problem that the filling of the metal is insufficient and micropores that are not filled with the metal remain, that is, there is a problem that the in-plane uniformity of the metal filling is inferior.

Therefore, it is an object of the present invention to provide a method for producing a metal-filled microstructure in which the in-plane uniformity of metal filling in micropores is good.

As a result of diligent research to achieve the above problems, the present inventor has subjected to anodization treatment, followed by a treatment of holding at a predetermined voltage for a certain period of time, and then an alkali containing a metal having a hydrogen overvoltage higher than that of aluminum. The present invention has been completed by finding that removing the barrier layer with an aqueous solution improves the in-plane uniformity of metal filling into micropores in the subsequent metal filling step.
That is, the present inventor has found that the above-mentioned problems can be solved by the embodiment shown in the following [1], and also found the preferred embodiments shown in the following [2] to [4].

[1] An anodizing treatment is applied to one surface of an aluminum substrate to form an anodic oxide film having micropores existing in the thickness direction and a barrier layer existing at the bottom of the micropores on one surface of the aluminum substrate. Anodization process and
After the anodizing treatment step, a holding step of holding the voltage at 95% or more and 105% or less of the holding voltage selected from the range of 1 V or more and less than 30% of the voltage in the anodizing treatment step for a total of 5 minutes or more.
After the holding step, a barrier layer removing step of removing the barrier layer of the anodized film using an alkaline aqueous solution containing ions of a metal M1 having a higher hydrogen overvoltage than aluminum,
After the barrier layer removal step, a metal filling step of plating and filling the inside of the micropore with metal M2,
A method for manufacturing a metal-filled microstructure, comprising a substrate removing step of removing an aluminum substrate to obtain a metal-filled microstructure after the metal-filling step.
[2] The method for producing a metal-filled microstructure according to [1], wherein the holding time in the holding step is 5 minutes or more and 10 minutes or less.
[3] The method for producing a metal-filled microstructure according to [1] or [2], wherein the voltage in the holding step is 5% or more and 25% or less of the voltage in the anodizing treatment.
[4] Described in any one of [1] to [3], wherein the voltage in the holding step is set to a voltage of 95% or more and 105% or less of the holding voltage within 1 second after the completion of the anodic oxidation treatment step. Method for manufacturing metal-filled microstructures.
[5] Production of the metal-filled microstructure according to any one of [1] to [4], wherein the metal M1 used in the barrier layer removing step is a metal having a higher ionization tendency than the metal M2 used in the metal filling step. Method.

According to the present invention, it is possible to provide a method for producing a metal-filled microstructure in which the in-plane uniformity of metal filling in micropores is good.

FIG. 1A is a schematic cross-sectional view showing an aluminum substrate to be anodized, which is a schematic cross-sectional view for explaining an example (first aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 1B is a schematic cross-sectional view showing a state after the anodic oxidation treatment step in a schematic cross-sectional view for explaining an example (first aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 1C is a schematic cross-sectional view showing a state after the holding step in a schematic cross-sectional view for explaining an example (first aspect) of the method for manufacturing a metal-filled microstructure of the present invention. FIG. 1D is a schematic cross-sectional view showing a state after the barrier layer removal step in a schematic cross-sectional view for explaining an example (first aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 1E is a schematic cross-sectional view showing a state after the metal filling step in a schematic cross-sectional view for explaining an example (first aspect) of the method for manufacturing a metal-filled microstructure of the present invention. .. FIG. 1F is a schematic cross-sectional view showing a state after the substrate removing step in a schematic cross-sectional view for explaining an example (first aspect) of the method for manufacturing a metal-filled microstructure of the present invention. .. FIG. 2A is a schematic cross-sectional view for explaining another example (second aspect) of the method for producing a metal-filled microstructure of the present invention, showing a schematic cross-sectional view showing an aluminum substrate to be anodized. It is a figure. FIG. 2B is a schematic cross-sectional view showing a state after the anodizing treatment step in a schematic cross-sectional view for explaining an example (second aspect) of the method for producing a metal-filled microstructure of the present invention. is there. FIG. 2C is a schematic cross-sectional view showing a state after the holding step in a schematic cross-sectional view for explaining an example (second aspect) of the method for manufacturing a metal-filled microstructure of the present invention. FIG. 2D is a schematic cross-sectional view showing a state after the barrier layer removing step in a schematic cross-sectional view for explaining an example (second aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 2E is a schematic cross-sectional view showing a state after the metal filling step in a schematic cross-sectional view for explaining an example (second aspect) of the method for manufacturing a metal-filled microstructure of the present invention. .. FIG. 2F is a schematic cross-sectional view showing a state after the surface metal projecting step in a schematic cross-sectional view for explaining an example (second aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 2G is a schematic cross-sectional view showing a state after the substrate removing step in a schematic cross-sectional view for explaining an example (second aspect) of the method for manufacturing a metal-filled microstructure of the present invention. .. FIG. 2H is a schematic cross-sectional view showing a state after the back metal projecting step in a schematic cross-sectional view for explaining an example (second aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 3A is a schematic cross-sectional view for explaining another example (third aspect) of the method for producing a metal-filled microstructure of the present invention, showing a schematic cross-sectional view showing an aluminum substrate to be anodized. It is a figure. FIG. 3B is a schematic cross-sectional view showing a state after the anodic oxidation treatment step in a schematic cross-sectional view for explaining an example (third aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 3C is a schematic cross-sectional view showing a state after the holding step in a schematic cross-sectional view for explaining an example (third aspect) of the method for manufacturing a metal-filled microstructure of the present invention. FIG. 3D is a schematic cross-sectional view showing a state after the barrier layer removing step in a schematic cross-sectional view for explaining an example (third aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 3E is a schematic cross-sectional view showing a state after the metal filling step in a schematic cross-sectional view for explaining an example (third aspect) of the method for manufacturing a metal-filled microstructure of the present invention. .. FIG. 3F is a schematic cross-sectional view showing a state after the resin layer forming step in a schematic cross-sectional view for explaining an example (third aspect) of the method for manufacturing a metal-filled microstructure of the present invention. is there. FIG. 3G is a schematic cross-sectional view showing a state after the substrate removing step in a schematic cross-sectional view for explaining an example (third aspect) of the method for manufacturing a metal-filled microstructure of the present invention. .. FIG. 4 is a schematic view illustrating an example of a supply form of the metal-filled microstructure produced by the method for producing a metal-filled microstructure of the present invention. FIG. 5A is a schematic view showing a voltage drop pattern when the voltage drops from the voltage in the anodizing process to the voltage in the holding process. FIG. 5B is a schematic view showing a voltage drop pattern when the voltage drops from the voltage in the anodizing process to the voltage in the holding process. FIG. 5C is a schematic diagram showing a voltage drop pattern in which the voltage in the anodizing process is dropped to 0 V at once and the holding step is not provided. FIG. 5D is a schematic diagram showing a voltage drop pattern in which the voltage in the anodizing process is continuously reduced to 0 V and the holding process is not provided. FIG. 6 is a schematic cross-sectional view showing a first example of a semiconductor package. FIG. 7 is a schematic cross-sectional view showing a second example of the semiconductor package. FIG. 8 is a schematic cross-sectional view showing a third example of the semiconductor package. FIG. 9 is a schematic cross-sectional view showing a fourth example of the semiconductor package. FIG. 10 is a schematic cross-sectional view showing a fifth example of the semiconductor package. FIG. 11 is a schematic cross-sectional view showing a configuration in which semiconductor package substrates are laminated. FIG. 12 is a schematic cross-sectional view showing a sixth example of the semiconductor package. FIG. 13 is a schematic cross-sectional view showing a seventh example of the semiconductor package. FIG. 14 is a schematic cross-sectional view for explaining the coaxial structure. FIG. 15 is a schematic plan view for explaining the coaxial structure.

[Manufacturing method of metal-filled microstructure]
In the method for producing a metal-filled microstructure of the present invention (hereinafter, also abbreviated as "the production method of the present invention"), one surface of an aluminum substrate (hereinafter, also referred to as "one side") is anodized and anodized. After the anodic oxidation treatment step of forming an anodic oxide film having a micropore existing in the thickness direction and a barrier layer existing at the bottom of the micropore on one surface of the aluminum substrate, and the anodic oxidation treatment step, Holding the aluminum substrate after the anodization treatment at a voltage of 95% or more and 105% or less of the voltage (holding voltage) selected from the range of 1 V or more and less than 30% of the voltage in the anodization treatment step for a total of 5 minutes or more. After the step and the holding step, a barrier layer removing step of removing the barrier layer of the anodic oxide film and a barrier layer removing step using an alkaline aqueous solution containing ions of a metal M1 having a hydrogen overvoltage higher than that of aluminum. After that, a metal filling step of performing a plating treatment to fill the inside of the micropore with metal M2, and a substrate removing step of removing the aluminum substrate to obtain a metal-filled microstructure after the metal filling step. It is a method of manufacturing a metal-filled microstructure having.

In the present invention, as described above, after the anodization treatment, the barrier layer is held at a predetermined voltage for a certain period of time, and then the barrier layer is formed by using an alkaline aqueous solution containing a metal having a hydrogen overvoltage higher than that of aluminum. By removing the metal, the in-plane uniformity of metal filling into the micropores in the subsequent metal filling step becomes good.
The reason is not clear in detail, but it is presumed to be as follows.
First, regarding the production method described in Patent Document 1 (International Publication No. 2015/029881), it was examined that the in-plane uniformity may be inferior depending on the conditions of the electrolytic plating treatment. As a result, it was acidic during the electrolytic plating treatment. When the plating solution of (for example, an aqueous solution of copper sulfate) is used, hydrogen gas is observed to be generated at the bottom of the micropore from which the barrier layer has been removed, that is, on the surface of the exposed aluminum substrate. It is known that the cause is that the presence of hydrogen gas once generated makes it difficult for the subsequent plating solution to penetrate into the micropores.
Further, when the cause of the inferior in-plane uniformity was examined with respect to Comparative Examples 3, 6 and 7 described later, it was found that the cause was the non-uniform dissolution of the barrier layer.
On the other hand, in the production method of the present invention, the barrier layer is thinned by performing a treatment of holding at a predetermined voltage for a certain period of time after the anodizing treatment step, and the dissolution in an alkaline aqueous solution easily and uniformly proceeds. it is conceivable that. Further, before the metal filling step, the barrier layer is removed by using an alkaline aqueous solution containing ions of metal M1 having a higher hydrogen overvoltage than aluminum, thereby not only removing the barrier layer but also exposing it to the bottom of the micropore. It is considered that a metal layer of metal M1 that is less likely to generate hydrogen gas than aluminum is formed on the aluminum substrate, and as a result, the generation of hydrogen gas by the plating solution is suppressed and the metal filling by the plating process is facilitated.
Here, in the method for manufacturing a metal-filled microstructure, the uniformity of barrier layer removal consists of the uniformity of thinning of the barrier layer and the uniformity of dissolution of the barrier layer, and the uniformity of metal filling during the plating process. It is thought that it has a great effect on sex.
It has been difficult to obtain the voltage control accuracy required to uniformly thin the barrier layer with the conventionally used electrolyzed power supply, but the recent improvement in voltage control accuracy has made it possible to maintain a low voltage precisely. As a result, the barrier layer can be thinned uniformly. As a result, the uniformity of dissolution of the barrier layer has a greater effect on the uniformity of metal filling than when the conventional method of manufacturing a metal-filled microstructure using a power source for electrolytic treatment is used. ..
The present inventor has combined the uniform thinning of the barrier layer by such precision holding of a low voltage with the application of an alkaline aqueous solution containing the ions of the metal M1 in the barrier layer removing step, during the plating process. It was found that the uniformity of metal filling is greatly improved.
Although the detailed mechanism is unknown, aluminum and anodized film are formed by forming a layer of metal M1 under the barrier layer by using an alkaline aqueous solution containing ions of metal M1 having a higher hydrogen overvoltage than aluminum in the barrier layer removal process. It is considered that this is because the interface between the two layers can be suppressed from being damaged and the uniformity of dissolution of the barrier layer is improved.

Next, the outline of each step in the manufacturing method of the present invention will be described with reference to FIGS. 1A to 1F, FIGS. 2A to 2H, and FIGS. 3A to 3G, and then the aluminum substrate and aluminum used in the manufacturing method of the present invention. Each processing step applied to the substrate will be described in detail.

<First aspect>
As shown in FIGS. 1A to 1F, in the metal-filled microstructure 10, one side of the aluminum substrate 1 is anodized, and one side of the aluminum substrate 1 has micropores 2 and micropores 2 existing in the thickness direction. 1V or more and less than 30% of the voltage in the anodic oxidation treatment step after the anodic oxidation treatment step (see FIGS. 1A and 1B) for forming the anodic oxide film 4 having the barrier layer 3 existing at the bottom and the anodic oxide treatment step. The barrier layer 3 of the anodic oxide film 4 is removed after the holding step (see FIGS. 1B and 1C) of holding the holding voltage at 95% or more and 105% or less of the holding voltage selected from the above range for a total of 5 minutes or more. The barrier layer removing step (see FIGS. 1C and 1D), the metal filling step of filling the inside of the micropore 2 with the metal 5b (metal M2) after the barrier layer removing step (see FIGS. 1D and 1E), and the metal. It can be produced by a manufacturing method having a substrate removing step (see FIGS. 1E and 1F) for removing the aluminum substrate 1 after the filling step.
Here, as described above, in the production method of the present invention, the barrier layer 3 of the anodized film 4 is formed by using an alkaline aqueous solution containing ions of a metal M1 having a higher hydrogen overvoltage than aluminum in the barrier layer removing step. At the same time as the removal, a metal layer made of metal 5a (metal M1) is formed on the bottom of the micropore 2 (see FIGS. 1D, 2D, and 3D).

<Second aspect>
The production method of the present invention preferably has at least one of a front surface metal projecting step and a back surface metal projecting step described later.
For example, as shown in FIGS. 2A to 2H (hereinafter, these are collectively simply abbreviated as “FIG. 2”), in the metal-filled microstructure 10, one side of the aluminum substrate 1 is anodized and the aluminum substrate 1 is subjected to anodization treatment. An anodic oxidation treatment step (see FIGS. 2A and 2B) for forming an anodized film 4 having a micropore 2 existing in the thickness direction and a barrier layer 3 existing at the bottom of the micropore 2 on one side of the metal. A holding step of holding at a voltage of 95% or more and 105% or less of the holding voltage selected from the range of 1 V or more and less than 30% of the voltage in the anodization treatment step after the treatment step for a total of 5 minutes or more (see FIGS. 2B and 2C). ), A barrier layer removing step (see FIGS. 2C and 2D) for removing the barrier layer 3 of the anodized film 4 after the holding step, and a metal 5b (metal M2) inside the micropore 2 after the barrier layer removing step. After the metal filling step (see FIGS. 2D and 2E) and the metal filling step, the surface of the anodized film 4 on the side where the aluminum substrate 1 is not provided is partially removed in the thickness direction, and the metal filling step is performed. A surface metal projecting step (see FIGS. 2E and 2F) for projecting the filled metal 5 from the surface of the anodic oxide film 4, and a substrate removing step (FIGS. 2F and 2G) for removing the aluminum substrate 1 after the surface metal projecting step. (See) and, after the substrate removing step, the surface of the anodic oxide film 4 on the side where the aluminum substrate 1 is provided is partially removed in the thickness direction, and the metal 5 filled in the metal filling step is removed from the surface of the anodic oxide film 4. It can also be produced by a manufacturing method having a back surface metal projecting step (see FIGS. 2G and 2H).
Here, as shown in the second aspect of FIG. 2, the manufacturing method of the present invention includes both a front surface metal projecting step and a back surface metal projecting step (hereinafter, these are collectively referred to as a “metal projecting step”). Although it may be an embodiment, it may be an embodiment having either a front surface metal projecting step or a back surface metal projecting step.

<Third aspect>
The production method of the present invention preferably has a resin layer forming step described later.
For example, as shown in FIGS. 3A to 3G (hereinafter, these are collectively simply abbreviated as “FIG. 3”), in the metal-filled microstructure 10, one side of the aluminum substrate 1 is anodized and the aluminum substrate 1 is subjected to anodization treatment. An anodic oxidation treatment step (see FIGS. 3A and 3B) for forming an anodic oxide film 4 having a micropore 2 existing in the thickness direction and a barrier layer 3 existing at the bottom of the micropore 2 on one side of the surface, and anodic oxidation. A holding step of holding at a voltage of 95% or more and 105% or less of the holding voltage selected from the range of 1 V or more and less than 30% of the voltage in the anodization treatment step after the treatment step for a total of 5 minutes or more (see FIGS. 3B and 3C). ), A barrier layer removing step (see FIGS. 3C and 3D) for removing the barrier layer 3 of the anodized film 4 after the holding step, and a metal 5b (metal M2) inside the micropore 2 after the barrier layer removing step. (See FIGS. 3D and 3E) and a resin layer forming step of providing a resin layer on the surface of the anodic oxide film 4 on the side where the aluminum substrate 1 is not provided after the metal filling step (FIGS. 3E and 3E). It can be produced by a manufacturing method having a substrate removing step (see FIGS. 3F and 3G) for removing the aluminum substrate 1 after the resin layer forming step (see FIG. 3F).
Here, the third aspect shown in FIG. 3 is an aspect (see FIG. 4) intended to wind and supply the metal-filled microstructure 20 to be produced in a roll shape, and peels off the resin layer 7 at the time of use. By doing so, for example, it can be used as an anisotropic conductive member.

<Other aspects>
The production method of the present invention satisfies both the second aspect shown in FIG. 2 and the third aspect shown in FIG. 3, that is, the above-mentioned anodization treatment step, holding step, barrier layer removing step, metal filling step, and surface. The embodiment may include a metal projecting step, a resin layer forming step, a substrate removing step, and a back surface metal projecting step in this order.
Further, the production method of the present invention is an embodiment shown in FIG. 2 of Patent Document 1 (International Publication No. 2015/029881), that is, a part of the surface of an aluminum substrate is anodized using a mask layer having a desired shape. May be applied.

[Aluminum substrate]
The aluminum substrate used in the production method of the present invention is not particularly limited, and specific examples thereof include a pure aluminum plate; an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements; low-purity aluminum (for example, a recycled material). ) With high-purity aluminum vapor-deposited; a substrate on which the surface of a silicon wafer, quartz, glass, etc. is coated with high-purity aluminum by a method such as vapor deposition or sputtering; a resin substrate laminated with aluminum; and the like.

In the present invention, the surface of the aluminum substrate on which the anodizing film is provided by the anodizing treatment step described later preferably has an aluminum purity of 99.5% by mass or more, preferably 99.9% by mass or more. Is more preferable, and 99.99% by mass or more is further preferable. When the aluminum purity is in the above range, the regularity of the micropore arrangement becomes sufficient.

Further, in the present invention, it is preferable that the surface of one side of the aluminum substrate to be subjected to the anodizing treatment step described later is subjected to heat treatment, degreasing treatment and mirror finish treatment in advance.
Here, regarding the heat treatment, the degreasing treatment, and the mirror finish treatment, the same treatments as those described in paragraphs <0044> to <0054> of JP-A-2008-270158 can be performed.

[Anodizing process]
In the anodizing step, anodizing is performed on one side of the aluminum substrate, so that one side of the aluminum substrate has micropores existing in the thickness direction and a barrier layer existing at the bottom of the micropores. Is the process of forming.
For the anodic oxidation treatment in the production method of the present invention, a conventionally known method can be used, but from the viewpoint of increasing the regularity of the micropore arrangement and ensuring the anisotropic conductivity of the metal-filled microstructure, self-regulation It is preferable to use a chemical method or constant voltage processing.
Here, regarding the self-regulation method and the constant voltage treatment of the anodizing treatment, the same treatments as those described in paragraphs <0056> to <0108> and [FIG. 3] of JP-A-2008-270158 are performed. Can be applied.

<Anodizing treatment>
The average flow rate of the electrolytic solution in the anodizing treatment is preferably 0.5 to 20.0 m / min, more preferably 1.0 to 15.0 m / min, and 2.0 to 10.0 m / min. It is more preferably min.
The method for flowing the electrolytic solution under the above conditions is not particularly limited, but for example, a method using a general agitator such as a stirrer is used. In particular, it is preferable to use a stirrer whose stirring speed can be controlled by a digital display because the average flow velocity can be controlled. Examples of such a stirrer include "Magnetic stirrer HS-50D (manufactured by AS ONE)" and the like.

For the anodizing treatment, for example, a method of energizing an aluminum substrate as an anode in a solution having an acid concentration of 1 to 10% by mass can be used.
The solution used for the anodic oxidation treatment is preferably an acid solution, and is preferably sulfuric acid, phosphoric acid, chromium acid, oxalic acid, sulfamic acid, benzenesulfonic acid, amide sulfonic acid, glycolic acid, tartaric acid, apple acid and citric acid. Etc. are more preferable, and sulfuric acid, phosphoric acid, and oxalic acid are particularly preferable. These acids can be used alone or in combination of two or more.

The conditions of the anodic oxidation treatment cannot be unconditionally determined because they vary depending on the electrolytic solution used, but in general, the electrolytic solution concentration is 0.1 to 20% by mass, the liquid temperature is -10 to 30 ° C, and the current is current. The density is preferably 0.01 to 20 A / dm ² , the voltage is 3 to 300 V, the electrolysis time is preferably 0.5 to 30 hours, the electrolyte concentration is 0.5 to 15 mass%, the liquid temperature is -5 to 25 ° C, and the current density is high. More preferably, it is 0.05 to 15 A / dm ² , a voltage of 5 to 250 V, an electrolysis time of 1 to 25 hours, an electrolytic solution concentration of 1 to 10 mass%, a liquid temperature of 0 to 20 ° C., and a current density of 0.1 to 10 A. It is more preferably / dm ² , a voltage of 10 to 200 V, and an electrolysis time of 2 to 20 hours.

In the present invention, in the anodic oxidation treatment step, the metal-filled microstructure produced by the production method of the present invention (particularly, the third aspect described above) is wound with a predetermined diameter and a predetermined width as shown in FIG. From the viewpoint of supplying in the form of being wound around 21, the average thickness of the anodized film formed by the anodizing treatment is preferably 30 μm or less, and more preferably 5 to 20 μm. The average thickness is obtained by cutting the anodized film in the thickness direction with a focused ion beam (FIB) and cutting the cross section with a field emission scanning electron microscope (FE-SEM). ) Was taken, and a surface photograph (magnification of 50,000 times) was taken and calculated as an average value measured at 10 points.

[Holding process]
After the anodic oxidation treatment step, the holding step holds the voltage of 95% or more and 105% or less of the holding voltage selected from the range of 1 V or more and less than 30% of the voltage in the anodizing treatment step for a total of 5 minutes or more. It is a process to do. In other words, the holding step is performed at a voltage of 95% or more and 105% or less of the holding voltage selected from the range of 1 V or more and less than 30% of the voltage in the anodic oxidation treatment step after the anodic oxidation treatment step. This is a process of performing electrolytic treatment for a minute or more.
Here, the "voltage in the anodic oxidation treatment" is a voltage applied between the aluminum and the counter electrode. For example, if the electrolysis time by the anodic oxidation treatment is 30 minutes, the voltage maintained for 30 minutes. The average value.

In the present invention, the voltage in the holding step is 5% or more of the voltage in the anodic oxidation treatment from the viewpoint of controlling the thickness of the side wall of the anodic oxide film, that is, the thickness of the barrier layer to an appropriate thickness with respect to the depth of the micropores. It is preferably 25% or less, and more preferably 5% or more and 20% or less.

Further, in the present invention, the total holding time in the holding step is preferably 5 minutes or more and 20 minutes or less, and more preferably 5 minutes or more and 15 minutes or less, for the reason that the in-plane uniformity is further improved. It is preferably 5 minutes or more and 10 minutes or less, more preferably.
The holding time in the holding step may be 5 minutes or more in total, but is preferably 5 minutes or more continuously.

Further, in the present invention, the voltage in the holding step may be set by continuously or stepwise (step-like) dropping from the voltage in the anodic oxidation treatment step to the voltage in the holding step, but the in-plane uniformity is maintained. For the reason of further improvement, it is preferable to set the voltage to 95% or more and 105% or less of the holding voltage within 1 second after the completion of the anodic oxidation treatment step.

In the present invention, the holding step can be performed continuously with the anodic oxidation treatment step, for example, by lowering the electrolytic potential at the end of the anodic oxidation treatment step.
In the holding step, the same electrolytic solution and treatment conditions as those of the conventionally known anodizing treatment described above can be adopted for conditions other than the electrolytic potential.
In particular, when the holding step and the anodizing treatment step are continuously performed as described above, it is preferable to carry out the treatment using the same electrolytic solution.

[Barrier layer removal process]
The barrier layer removing step is a step of removing the barrier layer of the anodic oxide film by using an alkaline aqueous solution containing ions of a metal M1 having a hydrogen overvoltage higher than that of aluminum after the holding step.
In the production method of the present invention, the barrier layer is removed by the barrier layer removing step, and as shown in FIG. 1D, a metal layer 5a made of metal M1 is formed at the bottom of the micropore 2. Become.
Here, the hydrogen overvoltage means a voltage required for hydrogen to be generated. For example, the hydrogen overvoltage of aluminum (Al) is −1.66 V (Journal of the Chemical Society of Japan, 1982, (8). ), P1305-1313). An example of the metal M1 having a hydrogen overvoltage higher than that of aluminum and the value of the hydrogen overvoltage thereof are shown below.
<Metal M1 and hydrogen (1NH ₂ SO ₄ ) overvoltage>
-Platinum (Pt): 0.00V
-Gold (Au): 0.02V
-Silver (Ag): 0.08V
-Nickel (Ni): 0.21V
-Copper (Cu): 0.23V
-Tin (Sn): 0.53V
-Zinc (Zn): 0.70V

In the present invention, the barrier layer removing step is performed because it causes a substitution reaction with the metal M2 to be filled in the anodization treatment step described later and has less influence on the electrical characteristics of the metal filled inside the micropores. The metal M1 used in 1 is preferably a metal having a higher ionization tendency than the metal M2 used in the metal filling step described later.
Specifically, when copper (Cu) is used as the metal M2 in the metal filling step described later, examples of the metal M1 used in the barrier layer removing step include Zn, Fe, Ni, Sn and the like. Among them, Zn and Ni are preferably used, and Zn is more preferable.
When Ni is used as the metal M2 in the metal filling step described later, examples of the metal M1 used in the barrier layer removing step include Zn and Fe, and among them, Zn is preferably used.

The method of removing the barrier layer using such an alkaline aqueous solution containing the ions of the metal M1 is not particularly limited, and examples thereof include the same methods as those of conventionally known chemical etching treatments. The ion concentration of the metal M1 in the alkaline aqueous solution containing the ions of the metal M1 having a higher hydrogen overvoltage than that of aluminum is preferably 1 to 10000 ppm, more preferably 10 to 1000 ppm, and particularly preferably 100 to 500 ppm.

<Chemical etching process>
To remove the barrier layer by chemical etching treatment, for example, the aluminum substrate after the anodization treatment step is immersed in an alkaline aqueous solution, the inside of the micropores is filled with the alkaline aqueous solution, and then the opening of the micropores of the anodized film is formed. Only the barrier layer can be selectively dissolved by a method of bringing the side surface into contact with a pH buffer solution or the like.

Here, as the alkaline aqueous solution containing the ions of the metal M1, it is preferable to use at least one alkaline aqueous solution selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The temperature of the alkaline aqueous solution is preferably 10 to 60 ° C, more preferably 15 to 45 ° C, and particularly preferably 20 to 35 ° C.
Specifically, for example, 50 g / L, 40 ° C. phosphoric acid aqueous solution, 0.5 g / L, 30 ° C. sodium hydroxide aqueous solution, 0.5 g / L, 30 ° C. potassium hydroxide aqueous solution and the like are preferably used. Be done.
As the pH buffer solution, a buffer solution corresponding to the above-mentioned alkaline aqueous solution can be appropriately used.

The immersion time in the alkaline aqueous solution is preferably 5 to 120 minutes, more preferably 8 to 120 minutes, further preferably 8 to 90 minutes, and preferably 10 to 90 minutes. Especially preferable. Of these, 10 to 60 minutes is preferable, and 15 to 60 minutes is more preferable.

[Metal filling process]
The metal filling step is a step of performing a plating treatment after the barrier layer removing step to fill the inside of the micropores in the anodic oxide film with the metal M2.

<Metal M2>
The metal M2 is preferably an electrical resistivity of less materials 10 ³ Ω · cm, and specific examples thereof include gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), nickel (Ni), zinc (Zn) and the like are preferably exemplified.
Among them, from the viewpoint of electrical conductivity, Cu, Au, Al and Ni are preferable, Cu and Au are more preferable, and Cu is further preferable.

<Filling method>
As a method of plating treatment for filling the inside of the micropore with the metal M2, for example, an electrolytic plating method or an electroless plating method can be used.
Here, it is difficult to selectively deposit (grow) a metal in the pores with a high aspect ratio by a conventionally known electrolytic plating method used for coloring or the like. It is considered that this is because the precipitated metal is consumed in the pores and the plating does not grow even if electrolysis is performed for a certain period of time or longer.

Therefore, in the production method of the present invention, when the metal is filled by the electrolytic plating method, it is preferable to provide a rest period during pulse electrolysis or constant potential electrolysis. The rest time requires 10 seconds or more, preferably 30 to 60 seconds.
It is also desirable to add ultrasonic waves to promote the agitation of the electrolyte.
Further, the electrolytic voltage is usually 20 V or less, preferably 10 V or less, but it is preferable to measure the precipitation potential of the target metal in the electrolytic solution to be used in advance and perform constant potential electrolysis within the potential + 1 V. When performing constant potential electrolysis, it is desirable that cyclic voltammetry can be used in combination, and potentiostat devices such as Solartron, BAS, Hokuto Denko, and IVIUM can be used.

As the plating solution, a conventionally known plating solution can be used.
Specifically, an aqueous solution of copper sulfate is generally used for precipitating copper, but the concentration of copper sulfate is preferably 1 to 300 g / L, more preferably 100 to 200 g / L. preferable. Moreover, precipitation can be promoted by adding hydrochloric acid to the electrolytic solution. In this case, the hydrochloric acid concentration is preferably 10 to 20 g / L.
When depositing gold, it is desirable to use a sulfuric acid solution of tetrachloroauric acid and perform plating by AC electrolysis.

In the electroless plating method, it takes a long time to completely fill the pores made of micropores having a high aspect with metal. Therefore, in the production method of the present invention, it is desirable to fill the metal by the electrolytic plating method. ..

In the present invention, the barrier layer is removed by the barrier layer removing step, and the metal layer made of the metal M1 described above is formed at the bottom of the micropores. Therefore, as described above, hydrogen gas is generated by the plating solution. It is considered that the metal filling by the plating process became easier to proceed.

[Substrate removal process]
The substrate removing step is a step of removing the aluminum substrate after the metal filling step to obtain a metal-filled microstructure.
The method for removing the aluminum substrate is not particularly limited, and for example, a method for removing by melting is preferable.

<Melting aluminum substrate>
For the dissolution of the aluminum substrate, it is preferable to use a treatment liquid in which the anodized film is difficult to dissolve and aluminum is easily dissolved.
Such a treatment liquid preferably has a dissolution rate in aluminum of 1 μm / min or more, more preferably 3 μm / min or more, and further preferably 5 μm / min or more. Similarly, the dissolution rate for the anodized film is preferably 0.1 nm / min or less, more preferably 0.05 nm / min or less, and even more preferably 0.01 nm / min or less.
Specifically, it is preferably a treatment liquid containing at least one metal compound having a lower ionization tendency than aluminum and having a pH of 4 or less or 8 or more, and the pH is 3 or less or 9 or more. Is more preferable, and 2 or less or 10 or more is further preferable.

Such treatment liquids are based on acid or alkaline aqueous solutions and include, for example, manganese, zinc, chromium, iron, cadmium, cobalt, nickel, tin, lead, antimony, bismuth, copper, mercury, silver, palladium, platinum, etc. A treatment liquid containing a gold compound (for example, chloroplatinic acid), these fluorides, these chlorides and the like is preferable.
Of these, an acid aqueous solution base is preferable, and a chloride blend is preferable.
In particular, a treatment liquid obtained by blending a hydrochloric acid aqueous solution with mercury chloride (hydrochloric acid / mercury chloride) and a treatment liquid obtained by blending a hydrochloric acid aqueous solution with copper chloride (hydrochloric acid / copper chloride) are preferable from the viewpoint of treatment latitude.
The composition of such a treatment liquid is not particularly limited, and for example, a bromine / methanol mixture, a bromine / ethanol mixture, aqua regia, or the like can be used.

The acid or alkali concentration of such a treatment liquid is preferably 0.01 to 10 mol / L, more preferably 0.05 to 5 mol / L.
Further, the treatment temperature using such a treatment liquid is preferably −10 ° C. to 80 ° C., preferably 0 ° C. to 60 ° C.

Further, the aluminum substrate is melted by bringing the aluminum substrate after the metal filling step into contact with the treatment liquid described above. The method of contact is not particularly limited, and examples thereof include a dipping method and a spraying method. Above all, the dipping method is preferable. The contact time at this time is preferably 10 seconds to 5 hours, more preferably 1 minute to 3 hours.

[Metal protrusion process]
In the production method of the present invention, the front surface metal projecting step and / or the back surface metal projecting step is performed as shown in the second aspect and FIG. 2 described above for the reason that the metal bondability of the produced metal-filled microstructure is improved. It is preferable to have it.
Here, in the surface metal projecting step, a part of the surface of the anodized film on the side where the aluminum substrate is not provided is removed in the thickness direction after the metal filling step and before the substrate removing step. This is a step of projecting the metal M2 filled in the metal filling step from the surface of the anodized film.
In the back surface metal projecting step, after the substrate removing step, a part of the surface of the anodic oxide film on the side where the aluminum substrate is provided is removed in the thickness direction, and the metal is filled in the metal filling step. This is a step of projecting M2 from the surface of the anodized film.

Partial removal of the anodic oxide film in such a metal projecting step does not dissolve the above-mentioned metal M1 and metal M2 (particularly metal M2), but dissolves the anodic oxide film, that is, an aqueous acid solution or alkali that dissolves aluminum oxide. This can be done by contacting the aqueous solution with an anodized film having micropores filled with metal. The method of contact is not particularly limited, and examples thereof include a dipping method and a spraying method. Above all, the dipping method is preferable.

When an aqueous acid solution is used, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, or hydrochloric acid, or a mixture thereof. Above all, an aqueous solution containing no chromic acid is preferable because it is excellent in safety. The concentration of the aqueous acid solution is preferably 1 to 10% by mass. The temperature of the aqueous acid solution is preferably 25 to 60 ° C.
When an alkaline aqueous solution is used, it is preferable to use at least one alkaline aqueous solution selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The temperature of the alkaline aqueous solution is preferably 20 to 35 ° C.
Specifically, for example, a phosphoric acid aqueous solution of 50 g / L and 40 ° C., a sodium hydroxide aqueous solution of 0.5 g / L and 30 ° C. or a potassium hydroxide aqueous solution of 0.5 g / L and 30 ° C. are preferably used. ..
The immersion time in the acid aqueous solution or the alkaline aqueous solution is preferably 8 to 120 minutes, more preferably 10 to 90 minutes, and further preferably 15 to 60 minutes. Here, the immersion time means the total of each immersion time when the immersion treatment for a short time is repeated. A cleaning treatment may be performed between the immersion treatments.

Further, in the production method of the present invention, when the metal-filled microstructure to be produced is used as an anisotropic conductive member, the above-mentioned surface is improved in crimpability with an object to be adhered such as a wiring substrate. The metal projecting step and / or the back surface metal projecting step is preferably a step of projecting the metal M2 from the surface of the anodic oxide film by 10 to 1000 nm, and more preferably a step of projecting the metal M2 by 50 to 500 nm.

Further, in the manufacturing method of the present invention, when the metal-filled microstructure to be manufactured and the electrode are connected (joined) by a method such as crimping, the insulating property in the surface direction when the protruding portion is crushed is sufficiently sufficient. For the reason that can be secured, the aspect ratio (height of the protruding portion / diameter of the protruding portion) of the protruding portion formed by the front surface metal projecting step and / or the back surface metal projecting step is 0.01 or more and less than 20. It is preferably 6 to 20.

In the production method of the present invention, the conduction path made of metal formed by the above-mentioned metal filling step, substrate removing step, and arbitrary metal projecting step is preferably columnar, and the diameter thereof is more than 5 nm and 10 μm or less. It is preferably present, and more preferably 40 nm to 1000 nm.

Further, the conduction paths exist in a state of being insulated from each other by an anodic oxide film of an aluminum substrate, and the density thereof is preferably 20,000 pieces / mm ² or more, and 2 million pieces / mm ² The above is more preferable, 10 million pieces / mm ² or more is more preferable, 50 million pieces / mm ² or more is particularly preferable, and 100 million pieces / mm ² or more is most preferable.

Further, the distance between the centers of the adjacent conduction paths is preferably 20 nm to 500 nm, more preferably 40 nm to 200 nm, and further preferably 50 nm to 140 nm.

[Resin layer forming process]
In the production method of the present invention, it is preferable to have a resin layer forming step as shown in the above-mentioned third aspect and FIG. 3 for the reason that the transportability of the produced metal-filled microstructure is improved.
Here, the resin layer forming step is after the metal filling step (after the surface metal projecting step if the surface metal projecting step is provided) and before the substrate removing step, the anodic oxidation. This is a step of providing a resin layer on the surface of the film on the side where the aluminum substrate is not provided.

Specific examples of the resin material constituting the resin layer include ethylene-based copolymers, polyamide resins, polyester resins, polyurethane resins, polyolefin-based resins, acrylic resins, and cellulose-based resins. However, from the viewpoint of transportability and ease of use as an anisotropic conductive member, the resin layer is preferably a film with a peelable adhesive layer, and the adhesiveness is increased by heat treatment or ultraviolet exposure treatment. A film with an adhesive layer that becomes weak and can be peeled off is more preferable.

The film with an adhesive layer is not particularly limited, and examples thereof include a heat-peeling type resin layer and an ultraviolet (ultraviolet) peeling type resin layer.
Here, the heat-peeling type resin layer has adhesive strength at room temperature and can be easily peeled off only by heating, and most of them mainly use effervescent microcapsules or the like.
Specific examples of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer include rubber-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, and polyamide-based pressure-sensitive adhesives. , Urethane-based adhesives, styrene-diene block copolymer-based adhesives, and the like.
Further, the UV peeling type resin layer has a UV curable adhesive layer, and the adhesive strength is lost by curing so that the resin layer can be peeled off.
Examples of the UV-curable adhesive layer include a polymer in which a carbon-carbon double bond is introduced into the polymer side chain or the main chain or at the end of the main chain as the base polymer. As the base polymer having a carbon-carbon double bond, a polymer having an acrylic polymer as a basic skeleton is preferable.
Further, since the acrylic polymer is crosslinked, a polyfunctional monomer or the like can be included as a monomer component for copolymerization, if necessary.
The base polymer having a carbon-carbon double bond can be used alone, but UV-curable monomers and oligomers can also be blended.
It is preferable to use a photopolymerization initiator in combination with the UV curable adhesive layer in order to cure it by UV irradiation. Photopolymerization initiators include benzoin ether compounds; ketal compounds; aromatic sulfonyl chloride compounds; photoactive oxime compounds; benzophenone compounds; thioxanson compounds; camphorquinone; halogenated ketones; acylphosphinoxide; acyl Phosphonate and the like can be mentioned.

Commercially available products of the heat-release type resin layer include, for example, Intellimar [registered trademark] tapes (manufactured by Nitta Corporation) such as WS5130C02 and WS5130C10; 3198, No. 3198LS, No. 3198M, No. 3198MS, No. 3198H, No. 3195, No. 3196, No. 3195M, No. 3195MS, No. 3195H, No. 3195HS, No. 3195V, No. 3195VS, No. 319Y-4L, No. 319Y-4LS, No. 319Y-4M, No. 319Y-4MS, No. 319Y-4H, No. 319Y-4HS, No. 319Y-4LSC, No. 31935MS, No. 31935HS, No. 3193M, No. Riva Alpha [registered trademark] series (manufactured by Nitto Denko KK) such as 3193MS; and the like.

Commercially available products of the UV peeling type resin layer include, for example, ELP holders such as ELP DU-300, ELP DU-2385KS, ELP DU-2187G, ELP NBD-3190K, and ELP UE-2091J [registered trademark] (Nitto Denko). (Made by Lintec Corporation); Adwill D-210, Adwill D-203, Adwill D-202, Adwill D-175, Adwill D-675 (all manufactured by Lintec Corporation); Sumilite (registered trademark) FLS N8000 series (Sumitomo Bakelite) Co., Ltd.); UC353EP-110 (manufactured by Furukawa Electric Co., Ltd.);
ELP RF-7232DB, ELP UB-5133D (all manufactured by Nitto Denko KK); SP-575B-150, SP-541B-205, SP-537T-160, SP-537T-230 (all manufactured by Furukawa Electric Co., Ltd.) (Manufactured); etc. back grind tape can be used.

The method of attaching the film with the adhesive layer is not particularly limited, and the film can be attached using a conventionally known surface protective tape affixing device or laminator.

[Winding process]
In the production method of the present invention, the metal-filled microstructure is rolled with the resin layer after the above-mentioned arbitrary resin layer forming step for the reason that the transportability of the produced metal-filled microstructure is further improved. It is preferable to have a winding step of winding in a shape.
Here, the winding method in the winding step is not particularly limited, and for example, as shown in FIG. 4, a method of winding on a winding core 21 having a predetermined diameter and a predetermined width can be mentioned.

Further, in the production method of the present invention, from the viewpoint of ease of winding in the winding step, the average thickness of the metal-filled microstructure excluding the resin layer is preferably 30 μm or less, preferably 5 to 20 μm. Is more preferable. The average thickness was measured at 10 points by cutting a metal-filled microstructure excluding the resin layer with FIB in the thickness direction and taking a surface photograph (magnification of 50,000 times) of the cross section by FE-SEM. Calculated as an average value.

[Other processing processes]
In addition to the above-mentioned steps, the manufacturing method of the present invention includes a polishing step, a surface smoothing step, and a protective film formation described in paragraphs <0049> to <0057> of Patent Document 1 (International Publication No. 2015/029881). It may have a treatment and a washing treatment.
Further, from the viewpoint of manufacturing handleability and the use of the metal-filled microstructure as the anisotropic conductive member, various processes and types as shown below can be applied.

<Process example using temporary adhesive>
In the present invention, after the metal-filled microstructure is obtained by the substrate removing step, the metal-filled microstructure is fixed on a silicon wafer by using Temporary Bonding Materials and thinned by polishing. It may have a process.
Then, after the step of thinning the layer, after thoroughly cleaning the surface, the above-mentioned surface metal projecting step can be performed.
Next, a temporary adhesive having a stronger adhesive force than the previous temporary adhesive is applied to the surface on which the metal is projected and fixed on the silicon wafer, and then the silicon wafer bonded with the previous temporary adhesive is peeled off. Then, the back surface metal projecting step can be performed on the surface of the peeled metal-filled microstructure side.

<Example of process using wax>
In the present invention, even if there is a step of obtaining a metal-filled microstructure by the substrate removing step, fixing the metal-filled microstructure on a silicon wafer with wax, and thinning the layer by polishing. Good.
Then, after the step of thinning the layer, after thoroughly cleaning the surface, the above-mentioned surface metal projecting step can be performed.
Next, a temporary adhesive is applied to the surface on which the metal is projected and fixed on the silicon wafer, and then the wax is melted by heating to peel off the silicon wafer, and the surface on the peeled metal-filled microstructure side is peeled off. On the other hand, the back metal projecting step can be performed.
Although solid wax may be used, liquid wax such as Skycoat (manufactured by Nikka Seiko Co., Ltd.) can be used to improve the uniformity of coating thickness.

<Example of process for removing the substrate later>
In the present invention, after the metal filling step and before the substrate removing step, an aluminum substrate is subjected to a rigid substrate (for example, a silicon wafer, a glass substrate, etc.) using a temporary adhesive, wax, or a functional adsorption film. After fixing to, there may be a step of thinning the surface of the anodized film on the side where the aluminum substrate is not provided by polishing.
Then, after the step of thinning the layer, after thoroughly cleaning the surface, the above-mentioned surface metal projecting step can be performed.
Next, a resin material (for example, epoxy resin, polyimide resin, etc.), which is an insulating material, is applied to the surface on which the metal is projected, and then a rigid substrate can be attached to the surface by the same method as described above. For pasting with a resin material, select one whose adhesive strength is greater than the adhesive strength with a temporary adhesive or the like, and after pasting with the resin material, the rigid substrate pasted first is peeled off, and the above-mentioned substrate is attached. The removing step, the polishing step, and the back surface metal protrusion processing step can be performed in order.
As the functional adsorption film, Q-chuck (registered trademark) (manufactured by Maruishi Sangyo Co., Ltd.) or the like can be used.

In the present invention, it is preferable that the metal-filled microstructure is provided as a product in a state of being attached to a rigid substrate (for example, a silicon wafer, a glass substrate, etc.) by a peelable layer.
In such a supply form, when the metal-filled microstructure is used as a joining member, the surface of the metal-filled microstructure is temporarily bonded to the device surface, the rigid substrate is peeled off, and then the device to be connected is attached. The upper and lower devices can be joined by a metal-filled microstructure by installing in an appropriate place and heat-bonding.
Further, as the peelable layer, a heat peeling layer may be used, or a photopeeling layer may be used in combination with a glass substrate.

Further, in the production method of the present invention, each step described above can be carried out in a single sheet, or can be continuously processed on a web using an aluminum coil as a raw material.
Further, in the case of continuous treatment, it is preferable to set an appropriate cleaning step and drying step between each step.

According to the production method of the present invention having each of such treatment steps, a metal-filled microstructure in which a metal is filled inside a through hole derived from a micropore provided in an insulating base material made of an anodized film of an aluminum substrate. The body is obtained.
Specifically, according to the production method of the present invention, for example, in an anisotropic conductive member described in Japanese Patent Application Laid-Open No. 2008-270158, that is, in an insulating base material (anodized film of an aluminum substrate having micropores). In addition, a plurality of conduction paths made of conductive members (metals) penetrate the insulating base material in the thickness direction in a state of being insulated from each other, and one end of each of the conduction paths is one of the insulating base materials. It is possible to obtain an anisotropic conductive member which is exposed on the surface of the above and is provided in a state where the other end of each of the conduction paths is exposed on the other surface of the insulating base material.

[Semiconductor package]
The semiconductor package has a semiconductor element on at least one side of the metal-filled microstructure described above. Here, the semiconductor element is not particularly limited, and for example, a logic LSI (Large Scale Integration) (for example, ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), ASSP (Application Specific Standard Product), etc.) , Microprocessor (for example, CPU (Central Processing Unit), GPU (Graphics Processing Unit), etc.), Memory (for example, DRAM (Dynamic Random Access Memory), HMC (Hybrid Memory Cube), MRAM (Magnetic RAM) and PCM (Phase-Change Memory), ReRAM (Resistive RAM), FeRAM (Ferroelectric RAM: Ferroelectric RAM), Flash Memory (NAND (Not AND) Flash), etc.), LED (Light) Emitting Diode), (for example, mobile terminal microflash, in-vehicle, projector light source, LCD backlight, general lighting, etc.), power device, analog IC (Integrated Circuit), (for example, DC (Direct Current) -DC (for example) Direct Current) converters, isolated gate bipolar transistors (IGBTs), etc.), MEMS (Micro Electro Mechanical Systems), (eg acceleration sensors, pressure sensors, transducers, gyro sensors, etc.), wireless (eg GPS (Global Positioning System)) , FM (Frequency Modulation), NFC (Nearfield communication), RFEM (RF Expansion Module), MMIC (Monolithic Microwave Integrated Circuit), WLAN (WirelessLocalAreaNetwork), etc.), Discrete element, BSI (Back Side Illumination), CIS (Contact Image Senso) r), camera module, CMOS (Complementary Metal Oxide Semiconductor), Passive device, SAW (Surface Acoustic Wave) filter, RF (Radio Frequency) filter, RFIPD (Radio Frequency Integrated Passive Devices), BB (Broadband) and the like.
The semiconductor package is, for example, a complete one, and the semiconductor package alone exhibits a specific function such as a circuit or a sensor.

Next, among the above-mentioned methods for manufacturing a metal-filled microstructure, the semiconductor of the present invention is obtained by performing the following steps between the above-mentioned [metal filling step] and the above-mentioned [substrate removing step]. The method of manufacturing the package will also be described.

[Semiconductor package manufacturing method 1]
After the above-mentioned [metal filling step], the semiconductor element mounting step of mounting the semiconductor element on the surface of the above-mentioned metal-filled microstructure and joining the above-mentioned metal M2 and the electrode of the semiconductor element, and the molding of molding with resin. The semiconductor package 30 shown in FIG. 6 can be manufactured by a manufacturing method having the steps and the above-mentioned [substrate removing step] in this order.
FIG. 6 is a schematic cross-sectional view showing a first example of a semiconductor package. In FIGS. 6 to 14 shown below, the same components as those of the metal-filled microstructure 10 shown in FIG. 1F described above are designated by the same reference numerals, and detailed description thereof will be omitted.
In the semiconductor package 30 shown in FIG. 6, the semiconductor element 32 is placed on the surface 10a of the metal-filled microstructure 10, and is electrically connected to the metal-filled microstructure 10 by a solder ball 35. The surface 10a of the metal-filled microstructure 10 is covered with the mold resin 34 including the semiconductor element 32.

[Semiconductor device mounting process]
When mounting a semiconductor element on the metal-filled microstructure of the present invention, mounting by heating is involved, but mounting by thermocompression bonding including solder reflow and mounting by flip chip are from the viewpoint of uniform and reliable mounting. The maximum reached temperature is preferably 220 to 350 ° C, more preferably 240 to 320 ° C, and particularly preferably 260 to 300 ° C.
From the same viewpoint, the time for maintaining these maximum temperatures is preferably 2 seconds to 10 minutes, more preferably 5 seconds to 5 minutes, and particularly preferably 10 seconds to 3 minutes.
Further, from the viewpoint of suppressing cracks generated in the anodic oxide film due to the difference in thermal expansion coefficient between the aluminum substrate and the anodic oxide film, it takes 5 seconds at a desired constant temperature before reaching the above-mentioned maximum temperature reached. A method of performing heat treatment for 10 minutes, more preferably 10 seconds to 5 minutes, particularly preferably 20 seconds to 3 minutes can also be adopted. The desired constant temperature is preferably 80 to 200 ° C, more preferably 100 to 180 ° C, and particularly preferably 120 to 160 ° C.
Further, the temperature at the time of mounting by wire bonding is preferably 80 to 300 ° C., more preferably 90 to 250 ° C., and particularly preferably 100 to 200 ° C. from the viewpoint of reliable mounting. The heating time is preferably 2 seconds to 10 minutes, more preferably 5 seconds to 5 minutes, and particularly preferably 10 seconds to 3 minutes.

[Semiconductor package manufacturing method 2]
After the above-mentioned [metal filling step], an element mounting step of mounting a semiconductor element with a resin paste in which the surface of the above-mentioned metal-filled microstructure is filled with solder, silver paste, or a filler, and a molding step of molding with resin. The step of drilling a hole in the mold resin to expose the element electrode and the above-mentioned metal M2, the step of forming a wiring for electrically conducting the above-mentioned metal M2 and the electrode of the semiconductor element, and the above-mentioned wiring are covered. The semiconductor package 30 shown in FIG. 7 can be manufactured by a manufacturing method having an insulating layer forming step for forming an insulating layer and the above-mentioned [substrate removing step] in this order.
FIG. 7 is a schematic cross-sectional view showing a second example of the semiconductor package.
In the semiconductor package 30 shown in FIG. 7, the semiconductor element 32 is placed on the surface 10a of the metal-filled microstructure 10 and is electrically connected. The surface 10a of the metal-filled microstructure 10 is covered with the mold resin 34 including the semiconductor element 32. The mold resin 34 is formed with a hole 36 for forming a wiring for electrically conducting the electrode of the semiconductor element 32 and the metal M2 of the metal-filled microstructure 10. Wiring 37 passing through the hole 36 is provided. The wiring 37 electrically conducts the electrodes of the semiconductor element 32 and the metal M2 of the metal-filled microstructure 10. Further, an insulating layer 38 covering the wiring 37 is provided on the upper surface of the mold resin 34.

<Wiring formation process>
The wiring forming step described above is a step of forming wiring on at least one surface of the metal-filled microstructure described above.
Here, examples of the method for forming the above-mentioned wiring include a method of performing various plating treatments such as electroplating treatment, electroless plating treatment, and replacement plating treatment; sputtering treatment; vapor deposition treatment; and the like. Of these, from the viewpoint of high heat resistance, layer formation of only metal is preferable, and from the viewpoint of thick film, uniform formation and high adhesion, layer formation by plating treatment is particularly preferable. Since the above-mentioned plating treatment is a plating treatment for a non-conductive substance (metal-filled microstructure), a method of forming a thick metal layer by providing a reduced metal layer called a seed layer and then using the metal layer. Is preferably used.
The above-mentioned seed layer is preferably formed by a sputtering treatment. Further, electroless plating may be used for forming the above-mentioned seed layer, and the plating solution includes, for example, a main component such as a metal salt or a reducing agent, and for example, a pH adjuster, a buffer, or a complexing agent. , It is preferable to use a solution composed of auxiliary components such as an accelerator, a stabilizer and an improver.
The plating solutions include SE-650, 666, 680, SEK-670, 797, SFK-63 (all manufactured by Japan Kanigen), Melplate NI-4128, Emplate NI-433, and Emplate NI-411. Commercially available products such as (all manufactured by Meltex) can be appropriately used.
When copper is used as the material for the above-mentioned wiring, various electrolytic solutions containing sulfuric acid, copper sulfate, hydrochloric acid, polyethylene glycol and a surfactant as main components and adding various other additives can be used.

The wiring formed in this way is patterned by a known method according to the design of mounting the semiconductor element or the like. Further, a metal including solder can be provided again at a place where a semiconductor element or the like is actually mounted, and can be appropriately processed so as to be easily connected by thermocompression bonding, flip chip, wire bonding, or the like.
As a suitable metal, solder or a metal material such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), nickel (Ni) is preferable, and a semiconductor element or the like by heating is preferable. From the viewpoint of mounting, the method of providing Au or Ag via solder or Ni is preferable from the viewpoint of connection reliability.
Specifically, as a method of forming gold (Au) via nickel (Ni) on the copper (Cu) wiring on which the pattern is formed, a method of performing Ni strike plating and then applying Au plating is used. Can be mentioned.
Here, Ni strike plating is performed for the purpose of removing the surface oxide layer of the Cu wiring and ensuring the adhesion of the Au layer.
Further, for Ni strike plating, a general Ni / hydrochloric acid mixed solution may be used, or a commercially available product such as NIPS-100 (manufactured by Hitachi Chemical Co., Ltd.) may be used.
On the other hand, Au plating is performed for the purpose of improving wire bonding or solder wettability after performing Ni strike plating. In addition, Au plating is preferably generated by electroless plating, such as HGS-5400 (manufactured by Hitachi Chemical Co., Ltd.), Microfab Au series, Galvanomeister GB series, Precious Hub IG series (all manufactured by Tanaka Kikinzoku Co., Ltd.), etc. A commercially available treatment liquid can be used.

In addition, as an embodiment for connecting the metal-filled microstructure of the present invention to a semiconductor element or the like using the above-mentioned wiring, for example, a flip chip using a C4 (Controlled Collapse Chip Connection) bump, a solder ball, a Cu pillar, or the like. Connection and connection using a conductive particle array type anisotropic conductive film (ACF) can be mentioned, but the aspect of the present invention is not limited thereto.

[Coaxial structure]
In addition, as shown in FIGS. 14 and 15, for example, a plurality of wires connected to the ground wiring 73 around a plurality of linear conductors 70 through which a signal current flows are connected to the ground wiring 73 at predetermined intervals. The shaped conductor 70 can also be arranged. Since this structure is equivalent to that of a coaxial line, it can exert a shielding effect. Further, a plurality of linear conductors 70 connected to the ground wiring 73 are arranged between the plurality of linear conductors 70 arranged adjacent to each other and through which different signal currents flow. Therefore, it is possible to reduce the electrical coupling (capacitive coupling) that occurs between the plurality of linear conductors 70 that are arranged adjacent to each other and through which different signal currents flow, and the plurality of linear conductors 70 themselves through which the signal currents flow are noise. It can be suppressed from becoming a source. In FIG. 14, the plurality of linear conductors 70 through which the signal current flows are formed on the insulating base material 71, are electrically insulated from each other, and are electrically connected to the signal wiring 72. The signal wiring 72 and the ground wiring 73 are electrically connected to a wiring layer 75 electrically insulated by an insulating layer 74, respectively.

<Insulation layer forming process>
The above-mentioned insulating layer forming step is a step of forming the above-mentioned insulating layer.
The method for forming the above-mentioned insulating layer is not particularly limited, but when the resin described below is used as the above-mentioned insulating layer, for example, a method of laminating on the above-mentioned metal-filled microstructure using a laminator device, a spin coater device. A method of coating on the above-mentioned metal-filled microstructure using the above-mentioned method, a method of forming an insulating layer at the same time as joining the above-mentioned metal-filled microstructure and the above-mentioned semiconductor element using a flip-chip bonding device, and the like can be mentioned. ..

(Insulation layer)
The material of the insulating layer is not particularly limited as long as it is a material having high insulating properties, and specific examples thereof include inorganic insulators such as air, glass and alumina, and organic insulators such as resin. These may be used alone or in combination of two or more. Of these, it is preferable to use a resin because of its low cost and high thermal conductivity.

The above-mentioned resin material is preferably a thermosetting resin. As the above-mentioned thermosetting resin, at least one selected from the group consisting of epoxy resin, modified epoxy resin, silicone resin, modified silicone resin, acrylate resin, urethane resin, and polyimide resin is preferable, and epoxy resin and modified resin are used. Epoxy resin, silicone resin, and modified silicone resin are more preferable.
Further, as the above-mentioned resin, it is preferable to use a resin having excellent heat resistance, weather resistance, and light resistance.
Further, in order to give the above-mentioned resin a predetermined function, at least one selected from the group consisting of a filler, a diffusing agent, a pigment, a fluorescent substance, a reflective substance, an ultraviolet absorber, and an antioxidant is used. It can also be mixed.
An adhesive composition can also be used as the above-mentioned resin, for example, commonly known as underfill material (liquid), NCP (Non Conductive Paste) (paste), NCF (Non Conductive Film) (film). Examples thereof include adhesives for semiconductors, and dry film resists and the like can also be used.
Further, as the above-mentioned insulating layer, the conductive particle array type anisotropic conductive film (ACF) described as the above-mentioned wiring may be used.
However, in the present invention, the mode of the above-mentioned insulating layer is not limited to the above-mentioned one.

<Drilling process>
The drilling step can be considered as a physical method such as laser machining, drilling, dry etching, or a chemical method by wet etching, but is not limited to these methods.

[Semiconductor package manufacturing method 3]
On the surface of the metal-filled microstructure between the above-mentioned metal filling step and the above-mentioned semiconductor element mounting step or semiconductor element mounting step described in the above-mentioned semiconductor package manufacturing method 1 and the semiconductor package manufacturing method 2. The mask layer forming step of forming the mask layer, the filled metal removing step of removing the metal M2 and the metal M1 filled in the anodized film, and the mask layer removing step of removing the mask layer are performed in this order. The semiconductor package 30 shown in FIG. 8 can be manufactured by the manufacturing method.
FIG. 8 is a schematic cross-sectional view showing a third example of the semiconductor package.
The semiconductor package 30 shown in FIG. 8 has the same configuration as the semiconductor package 30 shown in FIG. 6, except that the structure of the metal-filled microstructure 10 is different. In the metal-filled microstructure 10, the resin 8 is filled in the portion from which the metal M2 and the metal M1 have been removed by the filling metal removing step. The metal-filled microstructure 10 and the semiconductor element 32 are electrically connected by a solder ball 35 provided on the metal 5 which has not been removed.

[Semiconductor package manufacturing method 4]
A mask layer is formed on the surface of the metal-filled microstructure between the above-mentioned metal filling step described in the above-mentioned semiconductor package manufacturing method 1 and the above-mentioned semiconductor package 2 and the above-mentioned semiconductor element mounting step or the above-mentioned semiconductor element mounting step. A mask layer forming step for forming the above-mentioned metal-filled microstructure, a metal-filled microstructure removing step for removing the above-mentioned metal-filled microstructure, and a resin-filling step for filling the portion from which the above-mentioned metal-filled microstructure has been removed with resin, and the above-mentioned The semiconductor package 30 shown in FIG. 9 can be manufactured by a manufacturing method having a mask layer removing step of removing the mask layer in this order.
FIG. 9 is a schematic cross-sectional view showing a fourth example of the semiconductor package.
The semiconductor package 30 shown in FIG. 9 has the same configuration as the semiconductor package 30 shown in FIG. 6, except that the structure of the metal-filled microstructure 10 is different. In the metal-filled microstructure 10, the portion removed by the metal-filled microstructure removing step is filled with the resin 9 by the resin filling step. The metal-filled microstructure 10 and the semiconductor element 32 are electrically connected by a solder ball 35 provided on the metal 5 which has not been removed.

<Mask layer forming process>
The above-mentioned mask layer forming step is a step of forming a mask layer having a predetermined opening pattern (opening) on the surface of the metal-filled microstructure after the above-mentioned [metal filling step].
In the above-mentioned mask layer, for example, after forming an image recording layer on the surface of the above-mentioned metal-filled microstructure, energy is applied to the above-mentioned image recording layer by exposure or heating to develop a predetermined opening pattern. It can be formed by a method or the like. Here, the material for forming the above-mentioned image recording layer is not particularly limited, and conventionally known materials for forming a photosensitive layer (photoresist layer) or a heat-sensitive layer can be used, and if necessary, an infrared absorber or the like can be used. Additives may also be included.

<Mask layer removal process>
The above-mentioned mask layer removing step is a step of removing the above-mentioned mask layer.
Here, the method for removing the above-mentioned mask layer is not particularly limited, and for example, the above-mentioned mask is used using a liquid that dissolves the above-mentioned mask layer and does not dissolve the above-mentioned aluminum substrate and the above-mentioned anodic oxide film. Examples thereof include a method of layer dissolution and removal. Examples of such a liquid include known developing solutions when a photosensitive layer and a heat-sensitive layer are used for the above-mentioned mask layer.

<Filled metal removal process>
The above-mentioned filling metal removing step is a step of removing the metal M2 and the metal M1 in the metal-filled microstructure existing below the opening of the above-mentioned mask layer. Here, the method for removing the metal M2 and the metal M1 described above is not particularly limited, and examples thereof include a method for dissolving the metal M2 and the metal M1 using a hydrogen peroxide solution, an acidic aqueous solution, or a mixed solution thereof. Be done.

<Metal-filled microstructure removal process>
The above-mentioned metal-filled microstructure removing step is a step of removing the metal-filled microstructure existing below the opening of the above-mentioned mask layer.
Here, the method for removing the metal-filled microstructure described above is not particularly limited, and examples thereof include a method for dissolving the anodic oxide film of the metal-filled microstructure using an alkaline etching aqueous solution or an acidic aqueous solution.

<Washing treatment>
It is preferable to wash with water after the completion of each of the above-mentioned treatment steps. Pure water, well water, tap water, or the like can be used for washing with water. A nip device may be used to prevent the treatment liquid from being brought into the next process.

[Semiconductor package manufacturing method 5]
The semiconductor package 30 shown in FIG. 10 is manufactured by a manufacturing method including a wiring layer forming step of forming at least one or more wiring layers on the surface of the exposed metal-filled microstructure after the above-mentioned [board removal step]. be able to.
FIG. 10 is a schematic cross-sectional view showing a fifth example of the semiconductor package.
The semiconductor package 30 shown in FIG. 10 has the same configuration as the semiconductor package 30 shown in FIG. 6 except that the wiring board 40 is provided on the back surface 10b of the metal-filled microstructure 10.
The wiring board 40 is provided with a wiring layer 44 on an insulating base material 42 having electrical insulation. One of the wiring layers 44 is electrically connected to the metal 5 of the metal-filled microstructure 10, and the other is electrically connected to the solder balls 45. As a result, signals and the like can be taken out from the semiconductor element 32 to the outside of the semiconductor package 30. Further, a signal, voltage, current or the like can be supplied to the semiconductor element 32 from the outside of the semiconductor package 30.

[Semiconductor package manufacturing method 6]
FIG. 11 shows a manufacturing method including the step of joining the semiconductor package and the package substrate on which the semiconductor element is mounted at least once after the wiring layer forming step of the above-mentioned [Semiconductor package manufacturing method 5]. As described above, a PoP (Package on Package) substrate 31 in which semiconductor package substrates are laminated can be manufactured.

FIG. 11 is a schematic cross-sectional view showing a configuration in which semiconductor package substrates are laminated.
In the PoP substrate 31 shown in FIG. 11, the semiconductor package substrate 30a and the semiconductor package substrate 30b are laminated and electrically connected by solder balls 58. The semiconductor package substrate 30a is provided with a wiring layer 46 on the surface 10a of the metal-filled microstructure 10. The wiring layer 46 is provided with, for example, two wirings 48 in the insulating layer 47. Each wiring 48 is electrically connected to one semiconductor element 32 by a solder ball 35. The wiring layer 46 and one semiconductor element 32 are covered with the mold resin 34.
Further, the wiring layer 50 is provided on the back surface 10b of the metal-filled microstructure 10. The wiring layer 50 is provided with two wiring layers 52 on an insulating base material 51. Each wiring layer 52 is electrically connected to the solder balls 35 via the metal 5 of the metal-filled microstructure 10.
In the semiconductor package substrate 30b, for example, electrodes 55 are provided on both sides of the substrate 54, and two electrodes 56 are provided in the central portion. Each electrode 56 in the central portion is electrically connected to the semiconductor element 32 via a solder ball 35, respectively. The electrodes 55 on both sides of the substrate 54 are electrically connected to the wiring layer 52 of the semiconductor package substrate 30a via solder balls 58, respectively.

[Semiconductor package manufacturing method 7]
According to a manufacturing method including the step of forming a hole in the insulating layer to expose the above-mentioned wiring under the above-mentioned insulating layer after the step of forming the insulating layer according to the above-mentioned [Semiconductor package manufacturing method 2]. The semiconductor package 30 shown in 12 can be manufactured. In this way, the component-embedded substrate can be manufactured.
FIG. 12 is a schematic cross-sectional view showing a sixth example of the semiconductor package.
The semiconductor package 30 shown in FIG. 12 has the same configuration as the semiconductor package 30 shown in FIG. 7, except that the insulating layer 38 is provided with a hole 39 for exposing the wiring 37.

The present invention is not limited to the above-described embodiment, and examples of the mounting embodiment include SoC (System on a chip), SiP (System in Package), PoP (Package on Package), and PiP (Polysilicon Insulater). Polysilicon), CSP (Chip Scale Package), TSV (Through Silicon Via) and the like.

More specifically, for example, the metal-filled microstructure of the present invention can be used as a ground portion and a heat conduction portion in addition to connecting a data signal and a power source of a semiconductor element alone.

Further, the metal-filled microstructure of the present invention can be used as a ground portion and a heat conduction portion in addition to connecting a data signal or a power source between two or more semiconductor elements. Examples of such an embodiment include those using the metal-filled microstructure of the present invention as an interposer in the following examples.
・ Three-dimensional SoC logic device (for example, a homogeneous substrate (multi-layered FPGA (Field Programmable Gate Array) layered on an interposer), a heterogeneous substrate (digital device, analog device, RF device, and RF device on the interposer) A stack of MEMS and memory) etc.)
-Three-dimensional SiP (Wide I / O) that combines logic and memory (for example, one in which a CPU and DRAM are stacked on or above an interposer, one in which a GPU and DRAM are stacked on or above an interposer, ASIC / FPGA and Wide I / O memory stacked on or above the interposer, APE and Wide I / O memory stacked on or above the interposer, etc.)
-2.5-dimensional heterogeneous substrate that combines SoC and DRAM

Further, the metal-filled microstructure of the present invention can also be used for electrical connection between the semiconductor package 30 and the printed wiring board 60 as shown in FIG. The printed wiring board 60 is provided on the back surface 10b of the metal-filled microstructure 10 of the semiconductor package 30. In the printed wiring board 60, for example, the wiring layer 64 is provided on the insulating base material 62 made of resin. The wiring layer 64 is electrically connected to the metal 5 on the back surface 10b of the metal-filled microstructure 10.

Further, the metal-filled microstructure of the present invention can also be used for connecting two or more semiconductor packages (PoP), and in this case, for example, the metal-filled microstructure of the present invention can be used on it. Examples thereof include two semiconductor packages arranged on the lower surface side and a mode in which they are connected via predetermined wiring.
Further, the metal-filled microstructure of the present invention can also be used for a multi-chip package in which two or more semiconductor elements are stacked on a substrate or placed flat. In this case, for example, An embodiment in which two semiconductor elements are laminated on the metal-filled microstructure of the present invention and connected via a predetermined wiring can be mentioned.

Further, the application of the metal-filled microstructure of the present invention is not limited to the above, and for example, an interposer that simplifies the wiring process can be produced by bonding with a silicon interposer or a glass interposer.
Further, the metal-filled microstructure of the present invention can also be used for connecting a printed wiring board or a flexible substrate and a rigid substrate, connecting flexible substrates to each other, connecting rigid substrates to each other, and the like. The metal-filled microstructure of the present invention can also be used as a probe and a heat sink for inspection equipment.

The final product in which the metal-filled microstructure of the present invention and the semiconductor package of the present invention as described above are used is not particularly limited, and for example, a smart TV, a mobile communication terminal, a mobile phone, a smartphone, a tablet. Terminals, desktop PCs (Personal computers), notebook PCs, network devices (routers, switching), wired infrastructure devices, digital cameras, game machines, controllers, data centers, servers, HPCs (high-performance computing), graphic cards, network servers , Storage, chipset, in-vehicle (electronic control device, driving support system), car navigation system, PND (Personal Navigation Device), lighting (general lighting, in-vehicle lighting, LED lighting, OLED (Organic Light Emitting Diode) lighting), TV, display , Display panels (LCD panels, organic EL panels, electronic paper), music playback terminals, industrial equipment, industrial robots, inspection equipment, medical equipment, white goods such as household appliances and household appliances, space equipment, aircraft Equipment, wearable devices and the like are preferably mentioned.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.

[Example 1]
<Manufacturing of aluminum substrate>
Si: 0.06% by mass, Fe: 0.30% by mass, Cu: 0.005% by mass, Mn: 0.001% by mass, Mg: 0.001% by mass, Zn: 0.001% by mass, Ti: A molten metal containing 0.03% by mass, the balance being Al and an aluminum alloy of unavoidable impurities was prepared, and after the molten metal treatment and filtration were performed, an ingot having a thickness of 500 mm and a width of 1200 mm was DC (Direct Chill). ) Made by the casting method.
Next, the surface was scraped to an average thickness of 10 mm by a surface milling machine, and then the heat was kept uniform at 550 ° C. for about 5 hours. When the temperature dropped to 400 ° C., the thickness was 2.7 mm using a hot rolling mill. It was made into a rolled plate.
Further, after heat treatment was performed at 500 ° C. using a continuous annealing machine, it was finished by cold rolling to a thickness of 1.0 mm to obtain an aluminum substrate made of JIS 1050 material.
After making this aluminum substrate 1030 mm wide, each of the following treatments was performed.

<Electropolishing treatment>
The aluminum substrate was subjected to an electrolytic polishing treatment using an electrolytic polishing liquid having the following composition under the conditions of a voltage of 25 V, a liquid temperature of 65 ° C., and a liquid flow velocity of 3.0 m / min.
The cathode was a carbon electrode, and the power source was GP0110-30R (manufactured by Takasago Seisakusho Co., Ltd.). The flow velocity of the electrolytic solution was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE Corporation).
(Electropolishing liquid composition)
・ 85% by mass phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 660 mL
・ Pure water 160mL
・ Sulfuric acid 150mL
・ Ethylene glycol 30 mL

<Anodizing process>
Next, the aluminum substrate after the electrolytic polishing treatment was anodized by a self-regulation method according to the procedure described in JP-A-2007-204802.
The aluminum substrate after the electrolytic polishing treatment was subjected to anodization treatment for 6 hours with an electrolytic solution of 0.50 mol / L oxalic acid under the conditions of a voltage of 40 V, a liquid temperature of 16 ° C., and a liquid flow rate of 3.0 m / min. An anodic oxide film having a thickness of 40 μm was obtained.
In the anodizing treatment, the cathode was a stainless electrode and the power source was GP0110-30R (manufactured by Takasago Seisakusho Co., Ltd.). A NeoCool BD36 (manufactured by Yamato Kagaku Co., Ltd.) was used as the cooling device, and a pair stirrer PS-100 (manufactured by EYELA Tokyo Rika Kikai Co., Ltd.) was used as the stirring and heating device. Further, the flow velocity of the electrolytic solution was measured using a vortex type flow monitor FLM22-10PCW (manufactured by AS ONE Corporation).

<Holding process>
Next, after the anodizing treatment step, an electrolytic treatment was performed in which the voltage was lowered to 10V in the voltage drop pattern shown in FIG. 5A and held at 10V for 12 minutes. The holding (electrolytic treatment) was performed under the same conditions as the anodizing treatment conditions in the anodizing treatment step, except for the voltage and time.

<Barrier layer removal process>
Next, after the holding step, an etching treatment is performed in which zinc oxide is dissolved in an aqueous sodium hydroxide solution (50 g / L) so as to be 2000 ppm, and the mixture is immersed at 30 ° C. for 150 seconds, and the micropores of the anodic oxide film are subjected to The barrier layer at the bottom of the was removed, and zinc (metal M1) was simultaneously deposited on the surface of the exposed aluminum substrate.
The average thickness of the anodized film after the barrier layer removing step was 30 μm.

<Metal filling process>
Next, an aluminum substrate was used as a cathode and platinum was used as a positive electrode for electrolytic plating.
Specifically, a metal-filled microstructure in which copper was filled inside the micropores was produced by performing constant current electrolysis using a copper plating solution having the composition shown below.
Here, for constant current electrolysis, a plating apparatus manufactured by Yamamoto Plating Tester Co., Ltd. is used, and a power source (HZ-3000) manufactured by Hokuto Denko Co., Ltd. is used to perform cyclic voltammetry in the plating solution for precipitation. After confirming the potential, the treatment was performed under the conditions shown below.
(Copper plating solution composition and conditions)
・ Copper sulfate 100g / L
・ Sulfuric acid 50g / L
・ Hydrochloric acid 15g / L
・ Temperature 25 ℃
・ Current density 10A / dm ²

<Substrate removal process>
Next, the aluminum substrate was dissolved and removed by immersing it in a mixed solution of copper chloride / hydrochloric acid to prepare a metal-filled microstructure.

[Examples 2 to 8]
A metal-filled microstructure was produced in the same manner as in Example 1 except that the conditions in the anodizing process and the holding process were changed to the conditions shown in Table 1 below.

[Comparative Examples 1 to 14]
A metal-filled microstructure was produced in the same manner as in Example 1 except that the conditions in the anodizing process and the holding process were changed to the conditions shown in Table 1 below.
In Table 1 below, Comparative Examples 1 to 3, 6 and 7 are described as FIG. 5C or FIG. 5D in the item of "voltage drop pattern" of the holding step, but any of these voltage drop patterns can be used. However, since the pattern does not have a holding process, the "voltage" and "time" of the holding process are both indicated as "-".

[Evaluation]
The in-plane uniformity and adhesion were evaluated for each metal-filled microstructure produced in Examples 1 to 8 and Comparative Examples 1 to 9 by the methods shown below. These results are shown in Table 1 below.

<In-plane uniformity>
During the fabrication of each metal-filled microstructure, FE-SEM was used immediately after the metal-filling process to take photographs of 10 laterally adjacent fields of view at a magnification of 50,000 times, and the micropores that were not filled with metal. The ratio of the number of unfilled micropores was calculated from the value obtained by dividing the number by the total number of micropores, and evaluated according to the following criteria.
AA: The proportion of micropores that are not filled with metal (hereinafter abbreviated as "unfilled ratio" in this paragraph) is less than 1%.
A: The unfilled rate is 1% or more and less than 5%.
B: The unfilled rate is 5% or more and less than 10%.
C: The unfilled rate is 10% or more and less than 20%.
D: The unfilled rate is 20% or more and less than 30%.
E: The unfilled rate is 30% or more and less than 50%.
F: The unfilled rate is 50% or more.

<Adhesion>
During the production of each metal-filled microstructure, the adhesion of the anodic oxide film to the aluminum substrate in the barrier layer removal step and the metal filling step was evaluated according to the following criteria.
A: The anodized film does not peel off from the aluminum substrate in the barrier layer removal step and the metal filling step, and peeling does not occur even if the aluminum substrate is bent.
B: The anodic oxide film does not peel off from the aluminum substrate in the barrier layer removing step and the metal filling step, and when the aluminum substrate is bent after the metal filling step, the anodic oxide film partially peels off from the aluminum substrate.
C: The anodic oxide film does not peel off from the aluminum substrate in the barrier layer removing step, and the anodic oxide film peels off from the aluminum substrate in the metal filling step.
D: The anodized film is peeled off from the aluminum substrate during the barrier layer removal process.
E: Metal does not precipitate in the metal filling step, or the upper layer of the anodic oxide film dissolves in the barrier layer removing step.

From the results shown in Table 1, the voltage in the anodizing process is lowered to 0 V at once, and if there is no holding process, the in-plane metal to be filled in the micropores is in-plane regardless of the presence or absence of the barrier layer removal process. It was found that the uniformity was inferior (Comparative Examples 1 and 7).
Further, when the voltage in the anodizing treatment step is continuously lowered to 0V and the holding step is not provided, the in-plane uniformity of the metal filled in the micropore is inferior regardless of the presence or absence of the barrier layer removing step. It was found (Comparative Examples 2, 3 and 6).
Furthermore, it was found that the in-plane uniformity of the metal filled in the micropores was inferior regardless of the presence or absence of the barrier layer removal step when either the voltage or the time condition in the holding step was not satisfied (comparison). Examples 4, 5, 8 and 9).
Furthermore, it was found that the in-plane uniformity of the metal to be filled in the micropores is inferior when the barrier layer removing step is not provided even when the holding step is provided after the anodizing treatment step (comparison). Examples 11-14).

On the other hand, it was found that by performing the holding step and the barrier layer removing step in this order after the anodizing treatment step, the in-plane uniformity of the metal to be filled in the micropores was improved (implementation). Examples 1-8).
In particular, from the comparison of Examples 1 to 5, it was found that when the holding time in the holding step was 5 minutes or more and 10 minutes or less, the in-plane uniformity of the metal to be filled in the micropores became better.
Further, from the comparison between Example 4 and Example 6 and the comparison between Example 5 and Example 7, the voltage in the holding step is 1 V or more within 1 second after the completion of the anodic oxidation treatment step, and the above. When the voltage is set to 95% or more and 105% or less of the holding voltage selected from the range of less than 30% of the voltage in the anodic oxidation treatment step, the in-plane uniformity of the metal to be filled in the micropore is further improved. It turned out.

1 Aluminum substrate 2 Micropore 3 Barrier layer 4 Anodized film 5a Metal M1
5b metal M2
5 Metal 7 Resin layer 10,20 Metal-filled microstructure 10a Front surface 10b Back surface 21 Winding core 30 Semiconductor package 30a Semiconductor package substrate 30b Semiconductor package substrate 31 PoP substrate 32 Semiconductor element 34 Mold resin 35, 45, 58 Solder balls 36, 39 Holes 37, 48 Wiring 38, 47, 74 Insulation layer 40 Wiring board 42, 51, 62, 71 Insulation base material 44, 46, 50, 52, 64, 75 Wiring layer 54 Board 55, 56 Electrode 60 Printed circuit board 70 Linear conductor 72 Signal wiring 73 Ground wiring

Claims (5)

An anode in which one surface of an aluminum substrate is anodized to form an anodic oxide film having a micropore existing in the thickness direction and a barrier layer existing at the bottom of the micropore on one surface of the aluminum substrate. Oxidation process and
After the anodizing treatment step, a holding step of holding the voltage at 95% or more and 105% or less of the holding voltage selected from the range of 1 V or more and less than 30% of the voltage in the anodizing treatment step for a total of 5 minutes or more.
After the holding step, a barrier layer removing step of removing the barrier layer of the anodized film using an alkaline aqueous solution containing ions of a metal M1 having a hydrogen overvoltage higher than that of aluminum.
After the barrier layer removing step, a metal filling step of performing a plating treatment to fill the inside of the micropore with metal M2,
A method for manufacturing a metal-filled microstructure, comprising a substrate removing step of removing the aluminum substrate to obtain a metal-filled microstructure after the metal-filling step. The method for producing a metal-filled microstructure according to claim 1, wherein the holding time in the holding step is 5 minutes or more and 10 minutes or less. The method for producing a metal-filled microstructure according to claim 1 or 2, wherein the voltage in the holding step is 5% or more and 25% or less of the voltage in the anodizing treatment. The invention according to any one of claims 1 to 3, wherein the voltage in the holding step is set to a voltage of 95% or more and 105% or less of the holding voltage within 1 second after the completion of the anodic oxidation treatment step. Method for manufacturing metal-filled microstructures. The metal-filled microstructure according to any one of claims 1 to 4, wherein the metal M1 used in the barrier layer removing step is a metal having a higher ionization tendency than the metal M2 used in the metal filling step. Production method.